Nearly three- quartesr of the world is covered by water.
The pacificocean has a larger surface area than all the dry land on earth.
Unfortunately, this water itself is on good for drinking.
It is too salty. However, the water that is evaporatd from it by the heat of the sun is not too salty.
Tiny drops of fresh water mix with the air and sometimes become clouds in the sky. If the water in the clouds grows too heavy it falls to earth again.
About four- fifth goes directly back into the sea. But if the rain falls on land, the fresh water can be used by the living things there.
Most of it, however, either returns to the sea in rivers or disappears to the sea in rivers or disappears underground.
There are several different sources of drinking water.
In some areas, dams prevent rivers from returning rainwater to the sae, Reservoirs are formed to provide drinking water all year round.
In other places, rainwater drains through the rarth’s surface and collects in lakes or rivers undernarth.
Some water under the sahara Desert in North Afirca has lain there for 25, 000 years.
Other underground water does not lie in one place but moves slowly downhill over hard rock.
Water like this is used by people at cases, wells and bore holes all over the world.
Hoever, the largest source of fresh water has never been used at all.
About 90% of all fresh water in the world is in Antarctica.
It is unusable because it is remote and is in the form of ice and snow.
When the word water is mentioned, nearly everybody firsh thinks of water for drinking.
But actually, in some countries, people drink only a samall percentage of the water they use.
In the UK, for example, each person uses an average of about 180 liters of water per day. Of that, only about 3% is used for cooking and drinking. People use most of the rest for washing dishes, clothes and themselves and in the toilet. In industries, water is used for a variety of purposes. It takes 1 liter of water to make 2 kilos of bread.
It is used in the producing of electricity and at atomic power stations.
Of course it is also used world- wide in the cultivation and irrigation of crops. So water now has a variety of uses.
As the population of the world grows, the demand for water will increase too.
It may become even more precious than it is today.